The origin of this invention is traceable to U.S. Pat. No. 4,747,410 issued May 31, 1988 to the inventor herein. For that reason, the content of that patent is incorporated herein by reference.
It is axiomatic that each person is an individual and that problems associated with each differs. As such, the particular biomechanical requirements of each depends on both individual characteristics and the degree of the existing problem. For purposes of illustration, the example of biomechanical and kinesiological aspects of a sprained ankle is first discussed.
One of the most common injuries to the lower extremities is the sprained ankle, a sprain being a wrenched or twisted joint. The major components of the ankle joint are the distal ends of the tibia and fibula bones of the leg and the talus bone of the foot. These bones are bound by the medial and lateral collateral ligaments. A sprain constitutes a trauma manifested as straining or rupturing to these ligaments. On page 177 of DuVrie's Surgery of the Foot, edited by Verne T. Inman, M.D., Ph.D., and published by The C. V. Mosby Co. in 1973, the nature of an ankle strain is described.
In normal locomotion (walking or running), the thrust of the body weight is transmitted from the leg into the talus, distributed through the foot and, finally, impacts on the supporting surface. If, during locomotion, the foot suddenly turns laterally, an abnormally large horizontal body-weight force vector is created. Generally, this force vector is directed laterally through the lateral collateral ligaments; the Anterior Talofibular Ligament, the Posterior Talofibular Ligament, the Anterior Inferior Tibiofibular Ligament and the Calicaneofibular Ligament. Lateral forces and trauma sustained by these ligaments are referred to as inversion. If the horizontal force is directed medially through the Deltoid Ligament, which occurs less frequently than lateral injuries, it is known as eversion. Since the body weight is abnormally directed to one of the ankle sides, it is not properly transferred through the foot. Such abnormally directed horizontal force, when sufficiently strong, overcomes the ligament structure resulting in a sprain or rupture. Certain naturally occurring congenital foot deformities such as a forefoot varus tibial varum or rearfoot inversion, all of which promote inversion of the ankle joint, augment the probability of and can exacerbate ankle sprains.
Among the conventional treatments for ankle sprains are the use of a rearfoot wedge; this wedge being elevated on the lateral aspect to artificially form a rearfoot eversion. Biomechanically, the eversion promoted by the rearfoot wedge assists to prevent laterally directed ankle sprains. Unfortunately, the use of a rearfoot wedge can create or augment excessive pronation syndrome and the associated adverse physiological problems. Furthermore, reliance solely on a rearfoot wedge deprives the user of direct control over the ankle joint itself. Finally, use of a static single action rearfoot wedge while adequate in many cases, does not permit variable progressive treatment of an ankle sprain or strain. The ankle trauma version of the present invention is intended to overcome the disadvantages of the rearfoot wedge and provide for direct control over the inversion or eversion of the ankle joint.
Another commonly encountered foot injury involves heel spurs. Heel spur syndrome is caused by plantar fascial injuries developed from excess tensioning or pulling stress by the plantar fascia on the calcaneus. As a result, the membrane surrounding the calcaneus (periosteum) becomes inflamed. Since the periosteum has osteoblastic properties, the inflamed area ultimately calcifies and forms a sharp bony protuberance. The protuberance not only has the capability to traumatize but may develop sufficiently to cut surrounding soft tissue. Given the adverse effect of pronation on the plantar fascia, it follows that excessive pronation augments the stress on the periosteum. As the subtalar joint pronates, which in turn results in elongation of the foot, the plantar fascia stretches and creates corresponding tensioning of the plantar fascia.
Full treatment of heel spurs generally involves surgery. However, if attended to in the early stages, the development of periosteum inflammation and the corresponding spur formation can be halted. Thus, surgery, required for the more aggravated cases, can be avoided.